AJP - Gastrointestinal and Liver Physiology, Vol 269, Issue 4 584-G590, Copyright © 1995 by American Physiological Society
Effect of 17-norleucine-VIP on gastroduodenal motility relative to serum VIP concentration and blockade of NOS
G. E. Holle, E. Steinbach, E. Wunsch and J. J. Holst
Gastroenterology Research Laboratory, Ludwig Maximilian University, Munich, Germany.
Mechanical and electrical activity in the antrum, pylorus, and duodenum was
evaluated in the conscious dog, instrumented with seven strain gauges and
five platinum electrodes. 17-Norleucine-vasoactive intestinal peptide
(17-N-Leu-VIP) or 17-N-Leu-VIP plus NG-nitro-L-arginine methyl ester
(L-NAME) was injected intra-arterially close to the pylorus to identify
influences of nitric oxide (NO) on effects of VIP. VIP concentration was
measured by radioimmunoassay in serum samples collected from the cubital
and portal veins before and up to 2 h after VIP injection. VIP (0.004-0.006
mg.kg-1.10 min-1) abolished phasic contractions in the interdigestive state
for 16.8 min and in the digestive state for 14.4 min, whereas whole serum
VIP concentration rose above 42.4 +/- 13 pmol/l. Administration of L-NAME
did not significantly influence the effects of VIP. Aftereffects of VIP,
consisting of a reduced motility index, lasted 33 +/- 10.6 min in the
interdigestive state and 44.5 +/- 42 min in the digestive state. This VIP
aftereffect in the interdigestive state was shortened in time by the
addition of L-NAME. The results overall suggest that NO release is a factor
only in the aftereffects of VIP.
